3. A Simple Science Lens

In the previous chapter we took a basic view of simple science, looking
at it through the lenses of energy and force, matter, space and time. In
this chapter we continue our challenging journey showing how we can look
afresh and in detail at a single scientific principle, for which we have
chosen friction.

Please note that this is not intended as a complete treatise on the subject
nor does it cover all parts of science. What it does aim to do is indicate how
you can look at scientific subjects in simple, unscientific and unconventional
ways that allow you to see things differently and consequently make use of them
in your inventions.

Friction might be considered as being well understood, but scientists are
still debating this point. In fact, as with pressure, it can be said that that
friction doesn’t exist! This may seem to be a rather alarming statement, but let
us consider the real situation. In fact we will use friction as a particular
example of looking in detail at what at first may seem to be a simple and
well-understood problem.

If you have a bowl of fruit and you want to invent a way of making it more
green, you could think of is as an ‘inventing with light’ problem and, before
thinking about what you might change, ask what kinds of different light there
is. For example, you could make it more green by adding green things to the
bowl, you could remove some of the red and yellow fruit, or you could even put
it next to a green plant.

Friction is like the colour in the fruit bowl: it is made up of several
different things. To change friction, we need to identify and understand these
different components.

A good, creative starting point is to review the definition and get a fresh
view of the problem. The Concise Oxford English Dictionary describes it as
‘resistance a body encounters in moving over another.’ So it is about what stops
things that are in contact with one another from moving relative to one another.

Sections in this chapter:

The slippery case of ice

Most substances behave in predictable ways so we can have some
good guesses and see what ideas arise. But exceptions occur, and a
simple one is water.

For most liquids, as you cool them down, the molecules move
closer together as they jiggle around less. When they have calmed
down and are close enough, they can then bind with other molecules,
forming the solid. Because the molecules are closer together the
solid is denser than the liquid and will sink in it.

But water is funny. Icebergs are funny because they float. They
float because when water freezes it takes up more space (volume) not
less as most things do. It is just the way the molecules bind
together!

Now if you squeeze a solid, you will raise the temperature and it
will eventually liquefy as the molecular bonds are broken. So it
would seem that squeezing ice will turn it back into water, and
perhaps this is how ice skates work.
Wrong again. You need lots of pressure to liquefy a solid and the
pressure of ice skates is not enough to melt the ice.

So what is happening? It appears that at the surface of ice there
is a very thin layer of liquid molecules that form an excellent
lubricator. Along with a slight bow wave and the physical cutting
into the ice by the corners of the skates, this is how ice skating
works!